The present invention relates generally to the field of power driven cement finishers.
It has heretofore been generally known in the industry to provide electric and gas engine powered cement surface finishing machines in which a plurality of trowel blades are rotated about a common vertical axis. Machines of this type are exemplified by U.S. Pat. No. 2,198,929, dated Apr. 30, 1940, wherein the rotatable trowel blades have their tip extremities interconnected by a peripherally extending ring member which is rotatable with the blades. The exposed rotating blades in these known machines created a potential dangerous hazard to the operator and other personnel and in the event that the blade connecting ring should contact an object during operative movements of the machine, undesirable surface markings could result which marred or otherwise made it difficult to obtain the desired smoothly troweled surface.
Having in mind the problems of the known machines, as noted above, it is contemplated in the present invention to provide a stationary guard ring and supporting structure which will shield the rotating blades from inadvertent contact by operating and other personnel, and which will premit the machine to be moved into close areas where the guard ring might strike an object, but without causing the undesirable surface effects as would be produced by the heretofore known machines having a movable ring connected at the trowel tip ends.
In the development of the stationary guard ring concept, it was discovered that, when the ring support was connected directly to the main frame of the machine, there was a tendency for vibrations to be induced in the ring structure, and that these vibrations were conducted to the trowel blades. An undesirable condition was thus produced in that the vibrations of the blades were reflected in the form of ripples in the cement surface. It was therefore more or less impossible to obtain the desired smooth surface finish. This problem was overcome in the present invention by placing vibration absorbing means between the ring structure and the main frame structure of the machine.